Such a steering method and such an industrial truck have previously been described in DE 10 2010 016 470 B4. DE 10 2010 016 470 B4 describes an industrial truck with three wheels. All wheels are disposed so as to be steerable about steering axes that are approximately perpendicular to the wheel axles and that extend approximately parallel to each other. The industrial truck includes the steering programs “longitudinal travel” and “transverse travel.” A steering computer is provided to switch between longitudinal travel and transverse travel, oriented approximately perpendicularly thereto, via which the steering devices associated with the respective wheels can be acted on so that the wheels are in a neutral position of a steering element, for example, of a steering wheel in the straight-ahead position in the particular travel direction. In this position, all the rotational axes of the steered wheels run at least substantially parallel or congruently, in other words, the center of steering is in infinity.
All wheels of this vehicle can be driven by respective associated drive devices. These drive devices can in particular be electrically or hydraulically operated motors.
When this vehicle is in the “longitudinal travel” steering program, two of the wheels run in one and the same first track behind one another. The third wheel runs in the second track. Viewed in the longitudinal travel direction, this third wheel is located approximately between the two wheels running in the first track, and is thus also referred to as the “center wheel.”
When the vehicle is travelling longitudinally, the steering devices of the two wheels running in the first track are steered in accordance with steering commands generated by the steering element. The center wheel is not steered.
When the industrial truck is steered out of longitudinal travel into cornering, during which the center wheel is initially located on the inside of the curve, the rotational speed of the center wheel is reduced compared to the wheels located on the outside of the curve. When turning in, the center of steering of the two wheels running in the first track increasingly approaches the steering axis of the center wheel. The center wheel must be stopped when the center of steering coincides with the steering axis of the center wheel. When turning in further, the center wheel must finally rotate in the opposite direction, when the center of steering ends up between the center wheel and the wheels running in the first track, and the industrial truck thus rotates about a rotational axis located between the wheels and is thus in “carousel travel.”